cantilevered window

oriel

oriel 1. In medieval English architecture, chiefly residential, and derivatives: (a) a bay window corbeled out from the wall of an upper story; (b) a bay projecting, inside or out, extending a room; (c) a windowed bay or porch at the top of exterior stairs. 2. (rare) In medieval Continental structures and derivatives, a subsidiary bay, or a corbeled, enclosed feature, exterior or interior.